This invention relates to patient vascular catheterization and particularly to a catheterization system incorporating an anchoring feature for supporting a catheter tip within a blood vessel.
In various interventional medical procedures it is desirable to place a catheter within a patient's blood vessel for purposes of infusion of drugs or fluids, or for withdrawing blood. In some cases it is desirable to maintain an implanted catheter within the patient for a prolonged period of time, for example, for regional chemotherapy.
Often, implanted vascular catheters are used with so-called "infusion ports" which are placed subcutaneously and connected to an implanted catheter. In the past such infusion ports typically featured a compressed rubber septum which is penetrated by a hypodermic needle to provide fluid transfer with the implanted catheter. The present applicants are the inventors of a new generation of implantable infusion ports which do not rely on a compressed rubber septum, but instead use an articulating catheter valve. Examples of such devices are found in the following U.S. patent applications which are hereby incorporated by reference: Ser. No. 487,541, filed on Mar. 1, 1990 entitled; Cath-Link Vascular Access Port, Ser. No. 539,793, filed on Jun. 18, 1990 entitled; Implantable Infusion Device, and Ser. No. 654,661, filed on Feb. 15, 1991 entitled; Implantable Infusion Device. These new generation infusion ports broadly expand the access which the clinician has to an implanted catheter, enabling external catheters, guide wires, optical fibers, etc. to be placed into the implanted catheter.
While present techniques for implanting catheters within a patient's vascular tract are extremely useful for various procedures, they have significant limitations. The types of standard implanted catheters inserted by angiographic or surgical procedures tend to move about after implantation, which may result in dislodgement from the desired position. Such movement can also lead to the catheter tip perforating the blood vessel wall. As an alternative, in some circumstances catheters can be surgically implanted and anchored for maintaining their positions. Surgical catheter placement and tip fixation, however, involves hospitalization and major surgery.
As one means of anchoring the tip of a catheter within a patient, catheters having a preformed curled configuration have been employed. Such a catheter is temporarily straightened through the use of a semi-rigid guide wire or trocar which is passed through the lumen of the catheter. While such approaches have been successfully implemented for placement of catheters within the urinary bladder, abdominal cavity or stomach, they are impractical for use for anchoring a catheter within a blood vessel. The small diameter of blood vessels necessarily dictates an extremely small diameter catheter to enable the catheter to assume a curled configuration within the blood vessel. Such catheters would have poor flow rate capacities. Moreover, such a coiled configuration would predispose to clotting and then blockage of blood flow through the blood vessel, which is undesirable in most instances.
In accordance with the present invention, various anchoring elements are described for maintaining an implanted catheter tip at a desired position for prolonged periods of time. Each of the embodiments of this invention includes an anchoring element which is formed such that, in its free state, it expands to engage the inside wall of a blood vessel to mechanically link the implanted catheter tip to the blood vessel. Insertion, and in some cases removal of the catheter, is provided by retracting or deforming the anchoring element temporarily by using an introducer catheter which forms the anchoring element to a streamlined configuration, enabling it to be moved along within the vessel. In accordance with one embodiment, a helical coiled wire is used as the anchoring element and is straightened for implantation by pulling the coil inside an introducer catheter. In another embodiment, an anchoring element is employed having at least one expanding resilient leg which is retracted when the anchoring element is pulled inside the introducer catheter. Further described are systems for intentionally causing the anchoring element to occlude a blood vessel by generating a localized clot.
Additional benefits and advantages of the present invention will become apparent to those skilled in the art to which this invention relates from the subsequent description of the preferred embodiments and the appended claims, taken in conjunction with the accompanying drawings.